FIELD OF THE INVENTION

This invention relates to a fuel supply device in a vehicle.

In particular, this invention relates to a fuel supply device for an internal combustion engine.

BACKGROUND OF THE INVENTION

An internal combustion (IC) engine using diesel fuel works on a compression-ignition principle. As the name suggests in the compression-ignition principle, the diesel fuel has to be compressed to a high pressure value. The increase in pressure of the diesel increases the temperature of the diesel. The heat of compression of the diesel fuel is used to initiate ignition and burn the fuel in the combustion chamber of the diesel IC engine. Diesel IC engines do not use any igniters or spark plugs to ignite the fuel as the pressure and temperature of the diesel fuel is enough to ignite the fuel. However, one of most important aspects of a diesel IC engine is that the diesel has to be maintained at a particular pressure which aids in igniting the diesel fuel after it is introduced in the combustion chamber. To maintain pressure of diesel entering the combustion chamber, fuel supply devices known in the state of the art employ a common rail (Accumulator). The common rail type fuel injection systems house the add-on components such as Rail pressure sensor (RPS), Pressure control valve (PCV), sometimes a screw-plug. The rail has threaded connectors, depending on the number of cylinders/injectors in the specific system as outlet ports and corresponding inlet connector(s) to take-up the fuel from high pressure pump.

In a common rail type fuel supply device at least some volume of the diesel in always present in the common rail which helps in damping the pressure oscillations coming from the system. The common rail also has throttles in the high pressure connectors to aid in damping pressure oscillations. The common rail has two variants in terms of manufacturing. The first "LWR" Laser Welded Rail, employs the concept of machining the product from bar stock and then employing the process of Laser welding to fit-in the threaded connectors for high pressure pipes to injectors and from high pressure pump. The second concept, has forging as the basic principle of evolving the product geometry and then employs the machining for achieving the final geometries. The key factor that needs attention in the product is the fatigue strength, which is critical in achieving the lifetime requirements under the pulsating pressure loads. A pulsation test involving various pulsating pressures levels has to be successfully completed in order that the product be released for the application. (For eg: a pressure level means – pressure ranging from 50bar to 2400bar, Max pressure depending on the final pressure level that the product has to be released).

However, there are some disadvantages associated with the use and manufacturing of the common rail type fuel supply device. One of the disadvantages of the common rail type fuel supply device is that if there is even the slightest machining error in manufacturing the common rail would lead to failures in terms of pressure with-holding capacity in the rail. This pressure failure in the common rail would completely upset the injection and ignition cycle in a diesel IC engine. An error during welding in threaded connectors would add to the same failure as above. To Summarize, further to withstand not only the pressure pulsations but also to be able to store high pressure fuel in the common rail the material & processes has to be of a high standard. This would increase the cost of a fuel supply device which is implemented through a common rail type of device.

In case of modern low cost vehicle, where the main aim is to reduce the cost of the vehicle without compromising on quality and functionality the conventional common rail is high on cost. This also impacts the overall cost of the vehicle. The challenge here is to provide a low cost solution which provides the identical highly efficient functionality of the existing conventional common rail.

It is an object of this invention is to overcome the limitations of the conventional common rail type fuel supply devices.

ADVANTAGES OF THE INVENTION

The advantages of the invention as claimed in the independent claim are as follows. The fuel supply device of this invention has a first fuel distributor block, a second fuel distributor block and a pipe connecting the two fuel distributor blocks. Further a pressure sensor is integrated in the first fuel distributor block. This has the advantage that use of a common rail type (accumulator) of fuel supply device can be eliminated. The process of manufacturing the fuel supply device in accordance with this invention is much easier due to its compact size in comparison to rail. The cost of manufacturing the fuel supply device is much lower than that for manufacturing the common rail. Further, the fuel supply device has an integrated pressure sensor. The integrated pressure sensor provides the advantage of being able to monitor the pressure of fuel which is sent to the injectors to be injected into the combustion chamber in a diesel IC engine.

The fuel supply device has reduced high pressure volume which offers a cost optimized possibility to realize engine start almost at first TDC. The weight of the first fuel distributor block and second fuel distributor block is lower than the weight of common rail type fuel supply device this reduces the carbon-di-oxide emissions. The design of fuel distributor blocks can be standardized for any capacity of engine unlike the design for a common rail this enable better reliability testing. Standardization in design has the further advantage that no extra machining is required for new clamping fixtures and the like.

Further the pipe used to connect the first fuel distributor block and the second fuel distributor block is a simple pipe of a fixed capacity which is less expensive to manufacture than a specifically machined common rail.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS

Different modes of the invention are disclosed in detail in the description and illustrated in the accompanying drawing:

Figure 1 illustrates a fuel supply device in accordance with this invention;

Figure 2a illustrates the first fuel distributor block in accordance with this invention;

Figure 2b illustrates a sectional view of the first fuel distributor block of figure 2a;

Figure 3a illustrates the second fuel distributor block in accordance with this invention; and

Figure 4 illustrates a cut-section of the first fuel distributor block with the integrated pressure sensor.

DETAILED DESCRIPTION

Figure 1 illustrates a fuel supply device in accordance with this invention. The fuel supply device 10 comprises a first fuel distributor block 12 and a second fuel distributor block 14. The first fuel distributor block 12 and the second fuel distributor block 14 are adapted to be connected through a pipe 16. Further a pressure sensor 18 is located in the first fuel distributor block 12. As seen in figure 2a, the first fuel distributor block 12 comprises a first bore 20 and a second bore 22 intersecting each other and located in a first plane. A recess 24 and a bore 26 extend from the recess 24 towards point of intersection of the first bore 20 and second bore 22. The bore 26 is located in a plane perpendicular to first plane. A pressure sensor 18 located in the recess 24.

The first bore 20, second bore 22 and the recess 24 are internal to the first fuel distributor block 12 as seen in figure 2b. On the external surface the first fuel distributor block 12 has pluralities of external threaded interfaces 28. Each external threaded interface corresponds to each opening at the end of each bore. The first bore 20 has two external threaded interfaces 28 one each corresponding to each opening at the end of the first bore 20. The second bore has two external threaded interfaces 28 one each corresponding to each opening at the end of the second bore 22.

Figure 3a and 3b illustrates the second fuel distributor block 14 which has two internal bores 30 and 32 which are intersecting and perpendicular to each other. On the external surface of the second fuel distributor block 14 has pluralities of external threaded interfaces 34. Each external threaded interface corresponds to each opening at the end of each bore.

In the first fuel distributor block 12 the fuel enters the first fuel distributor block 12 via the first bore 20 from a fuel pump connected to one of the external threaded interfaces 28. The pipe 16 which connects the first fuel distributor block 12 and the second fuel distributor block is attached through one of the external threaded interfaces 28 on the first fuel distributor block 12 and on of the external threaded interfaces 24 on the second fuel distributor block 14. The pipe is usually attached to the threaded interface 28 which is opposite to the threaded interface 28 from which the fuel enters the first fuel distributor block 12. Through the external threaded interfaces 28 which are available at the end of the second bore 22, the fuel is supplied to the injectors via a high pressure connection attached to the external threaded interfaces 28.

In the second fuel distributor block 14 the fuel enter through the pipe 16 which connects the first fuel distributor block 12 and the second fuel distributor block 14. Through the remaining external threaded interfaces 34 on the second fuel distributor block 14 the fuel is supplied to pluralities of injectors via high pressure connection attached to the external threaded interfaces 34.

The pressure sensor 18 is an electronic controlled sensor which is housed in a housing 36. A housing 36 as seen in figure 4 is located in the recess 24 at the one end of the first fuel distributor block 12. The housing 36 holds all the components which allows the pressure sensor 18 to communicate with an electronic control unit (not shown in the drawings) which controls the fuel injection cycles of an engine. The recess 24 is provided with an internal thread which is used to screw in the housing 36 to the first fuel distributor block 12. The housing 36 is screw fit into the recess 24. The pressure sensor 18 is electronic controlled this ensures accuracy of measurement and better control of fuel injection cycles.

Figure 4 illustrates a cut-section of the first fuel distributor block 12 with the integrated pressure sensor 18. While manufacturing the first fuel distributor block 12 and the second fuel distributor block 14, with the right material care is taken that the sealing surfaces/ Intersections of the first 12 and second 14 fuel distributor blocks has specific geometric and form tolerances which ensure that it is able to withstand the high pressure exerted by the pressurized fuel which is received by the first fuel distributor block 12 from a high pressure fuel pump and delivered'-to pluralities of injectors. Further, the portion of the first bore 20 and the second bore 20 which intersect are designed in a manner such that it avoids any crack initiation in the first fuel distributor block 12 which may occur due to pulsating pressure levels that may be present at the intersection. Also, the portion of the bores 30 and 32 in the second fuel distributor block 14 which intersect are designed in a manner such that it has minimum stress concentration levels to avoid any crack initiation in the first fuel distributor block 12 which may occur due to pulsating pressure levels that may be present at the intersection.

Another important aspect of the first fuel distributor block 12 in accordance with this invention is the formation of the recess 24. The diameter of the recess 24 opening at one end of the first fuel distributor block 12 is larger than the opening of the recess 24 which is opens up into the bore 26. Due to the difference in diameters at the two end of the recess 24, a seat 38 is formed on which the housing 36 is seated when the fuel supply device 10 is in its operative configuration. When the housing 36 is screw fit into the seat 38, the pressure sensor 18 located in the housing 36 in a manner such that pressure sensor is in fluid communication with the pressurized fuel entering the fuel distributor block via the first bore 20. It is ensured by the right design parameters and manufacturing processes that there is no leakage of high pressure fuel at this sealing surface.

While designing the first fuel distributor block 12 care has to be take that the distance between the seat 38 formed by one end of the recess and the cross hole intersection of the first bore 20 and the second bore 22 is such that it can withstand the pressure exerted by the high pressure fuel entering the first bore 20. Also to reduce the stress concentration is the area around the cross holes, the sharp edge resulting from the two bores intersection is reworked generating a rounded surface, whose size, edge and surface quality provides greater potential strength. The positioning of the recess 24 in context with the positioning of the first bore 20, second bore 22 and the intersection of the two bores 20 and 22 ensures optimum fatigue strength to the fuel distributor block. The screwing process used to tighten the pressure sensor in the recess 24 ensures an accurate axial force.

The size of the first bore 20 and the second bore 22 also ensures that there is minimum volume of accumulated fuel in the fuel distributor block. This has the advantage that there is no issue with development and management of pressure pulsations within the fuel distributor block.

The HP (High Pressure) pipe 16 length between the first fuel distributor block 12 and the second fuel distributor block 14 acts as an accumulator in addition to the volume in the two blocks 12 and 14. The length of the pipe 16 can be varied depending on the application which provides a possibility to diversify the high pressure fuel volume. Also inner diameter of the pipe 16 can be varied so that fuel volume can be maintained at specific pressure value depending on the application. The variation in inner diameter of the pipe also contribute to better dampening of the pressure variation that may be experienced. As seen in figures the first fuel distributor block 12 and the second fuel distributor block 14 are provided with clearance holes which enable mounting of the fuel distributor block 12 and 14 onto the engine. Further the distributor blocks 12 and 14 are symmetrical in design allowing plurality of high pressure outlet through the external threaded interfaces 28. Also the clearance holes provided on the distributor block 12 and 14 are located diagonally opposite to each other to ensure better stability and minimum vibration levels while the fuel distributor blocks 12 and 14 are mounted onto the engine.

It must be understood that the embodiments explained above are only illustrative and do not limit the scope of the invention. Many modifications in embodiments are envisaged and form a part of this invention. The scope of the invention is only limited by the claims.

WE CLAIM:

1. A fuel supply device (10) for an internal combustion engine comprising:
(i) a first fuel distributor block (12); and
(ii) a second fuel distributor block (14); said first fuel distributor block (12) and said second fuel distributor block (14) adapted to be connected through a pipe (16).

2. A fuel supply device (10) as claimed in claim 1, wherein a pressure sensor (18) is located in said first fuel distributor block (12).

3. A fuel distributor block (12) comprising:

(i) a first bore (20) and a second bore (22) intersecting each other and located in a first plane;
(ii) a recess (24) and a bore (26) extending from said recess (24) towards point of intersection of said first bore (20) and second bore (22), said bore (26) located in a plane perpendicular to said first plane; and
(iii) a pressure sensor (18) located in said recess (24).

4. The fuel distributor block (12) as claimed in claim 3, wherein said fuel distributor block (12) comprises external threaded interfaces (28) corresponding to each end of said first bore (12) and each end of said second bore (14).

5. A fuel supply device (10) as claimed in claim 1, wherein said first fuel distributor block (12) is the fuel distributor block as claimed in claim 3.

6. A fuel supply device (10) as claimed in claim 1, wherein said second fuel distributor block (14) comprising at least two bores (30) and (32) located in the same plane and having external threaded interfaces (34) corresponding to each end of said two bores (30) and (32).

7. The fuel supply device (10) as claimed in claim 1, wherein fuel enters said first fuel distributor block (12) via said first bore (20) from a fuel pump connected to one of said threaded interfaces (28) of said first fuel distributor block (12).

8. The fuel supply device (10) as claimed in claim 1, wherein fuel in said first fuel distributor block (12) is supplied to pluralities of injectors through higher pressure connection engaged to said threaded interfaces (22) on said first fuel distributor block (12).

9. The fuel supply device (10) as claimed in claim 1, wherein fuel in said second fuel distributor block (12) said fuel is supplied to pluralities of injectors through higher pressure connection engaged to said threaded interfaces (32) on said second fuel distributor block (14).

10. The fuel supply device (10) as claimed in claim 1, wherein fuel in said first distributor block (12) flow into said second fuel distributor block (14) through said pipe (16).